Q: last aircraft design incorporating a dive-brake?

… In extremis you might pop the brakes if you’re wildly out of control, but even then you’d probably only be stopping the speed increasing rather than reducing it.
…
In my experience spoilers are rather less effective than airbrakes on glides, but this may just be the implementation in the gliders concerned.

Depends on the glider concerned. Any ‘classic’ wooden glider was built to the requirement of not exceeding Vne in a vertical dive with airbrakes extended, so will in most cases suffer a reduction of airspeed when airbrakes are deployed, rather than just stopping the increase (.e.g. 45 degree dive above Vm with airbrakes fully open will see a decrease generally). Same goes for some modern ships, but only in very shallow dives (a lot were built to the certification requirement of not exceeding Vne in a 45 degree dive with full airbrakes).

Spoilers are as you say quite ineffective on most gliders, and require sideslipping as well (T21, Rhönlerche, etc.) to properly reduce L/D. There’s hardly any of them used for that reason after the 1960s.

There is another form of airbrake, apart from the vertical one, hinged one at the back of the wing, and the spoiler system. Quite a fair few of aircraft from the 1940s to 1960s have peddles: spoilers hinging outwards from the wing (often above and below) on arms. Compare the T34 for instance.

I always understood the purpose of spoilers was to destroy lift and not specifically to reduce speed.

Depends on the phase of flight. In landing the are to reduce L/D and give you a far better way to aim for a tight landing than just sideslipping. In cloud flying (for which they were designed originally) they are specifically for reducing speed. Same with dives, intended or unintended.

Didn’t the Victor have air brakes the size barn doors?

SPoiler:

[ATTACH=CONFIG]228902[/ATTACH]

airbrake

[ATTACH=CONFIG]228903[/ATTACH]

trailing edge airbrake

[ATTACH=CONFIG]228904[/ATTACH]

the daddy of the all is this:

[ATTACH=CONFIG]228905[/ATTACH]

(asw20 with land flap, brakes etc will get the glide L/D all the way to 1:3 if you try hard 🙂

Are dive brakes on gliders the same as spoilers?

I always understood the purpose of spoilers was to destroy lift and not specifically to reduce speed.

In effect they are similar, but in practice in glider parlance, spoilers are a hinged flap is stowed flush with the top of the wing and hinges out into the airstream wheras airbrakes are a vertially oriented paddle stowed within the wing which deploy vertically into the airstream. Occasionally you find trailing edge airbrakes which are a hinged surface similar to a flap which deploys above and below the wing at the trailing edge
Both are used in practice to increase L/D (steepen the glide) and rarely to reduce speed – that’s what the elevator’s for. In extremis you might pop the brakes if you’re wildly out of control, but even then you’d probably only be stopping the speed increasing rather than reducing it.
Increasing L/d is achieved by reducing the lift coefficient a bit and increasing the drag which isn’t hard since the total drag on a modern glider is of the order of 10N or so, so not hard to increase significantly.
In my experience spoilers are rather less effective than airbrakes on glides, but this may just be the implementation in the gliders concerned.

Are dive brakes on gliders the same as spoilers?

I always understood the purpose of spoilers was to destroy lift and not specifically to reduce speed.

The F-105 had dive / speed brakes. The 4 “petals” at the end of the fuselage over the burner can were used. The 2 side ones were deployed on landing to function as speed breakes. All 4 were deployed as dive brakes to effectivly slow the a/c in a dive. Sitting on the ground you can see that after the hydraulics bleed off the 2 side petals would move out board slightly and the lower one would droop down. On most 105’s on historical display the petals are bolted together with metal straps and screws to prevent them from drooping and causing a safety hazard.
Cheers,
Itch

From my Airfix days, don’t I recall the Buccaneer having a spilt tailcone dive/speed brake?

Moggy

Quite correct, also used as a metod of shortening the aircraft to save space on the hangar deck as they opened to a 90 degree angle along with a hinged nose cone.

I’m also hearing that the speed brake is making the BAE-146 a bit of a sensation when it comes to the latest job that it has been assigned to. In the fire fighting role that it is now assuming, the speed brake makes it ideal for diving into box canyons to drop the retardant load.

From my Airfix days, don’t I recall the Buccaneer having a spilt tailcone dive/speed brake?

Moggy

I was told during my training on the BAE-146, that the speed brake design was taken directly from the Buccaneer.

From my Airfix days, don’t I recall the Buccaneer having a spilt tailcone dive/speed brake?

Moggy

But very impressive in the jump seat whilst approaching Marignane from the south ; )

The speed brakes on the BAE-146 also come to mind. I heard of crews deploying them to bleed off airspeed/altitude on very steep approaches. Hopefully with no one in the back….

Cobblers, gliders have airbrakes beacause its’ the easiest and simplest way to control the approach path, nothing to do with not shedding lift (which they do quite nicely – popping a socking great paddle up in the middle of a wing does that) or not being able to regain lift easily (eh?).

THe only method I can think of off the top of my head which doesn’t shed any lift is the drag chute but that’s a bit digital.

Technically, it is not about about shedding lift, but reducing L/D. Whilst reduction of lift (L) does occur in operating a glider’s dive brakes, it is the immense increase in drag (D) that does most of the trick. And it’s not just about controlling the glidepath on landing (but which is, I must admit, a very substantial part of it). Dive brakes in sailplanes were invented in the first place to reduce the chance of overloading the aircraft when control was lost in cloud flying. When they were not that common yet, most landings were sideslips…

Looking around on the net, dive-brakes seem to persist on gliders where it is critical that speed be limited in a dive without shedding lift, since it can’t be regained easily.

Cobblers, gliders have airbrakes beacause its’ the easiest and simplest most effective and user friendly way to control the approach path, nothing to do with not shedding lift (which they do quite nicely – popping a socking great paddle up in the middle of a wing does that) or not being able to regain lift easily (eh?).

THe only method I can think of off the top of my head which doesn’t shed any lift is the drag chute but that’s a bit digital.

Might I suggest every single sailplane being produced in the last few decades? Certification basis on the old wooden ships used to be that the aircraft should not exceed Vne in vertical dive with dive brakes extended. When GRP arrived and ships became sleeker, this was modified to not exceed Vne in a 45-degree dive with dive brakes extended.

The official term for the brake assembly on the EE Canberra is “dive brake” (or was on 39(1 PRU) Sqn up until its disbandment in ’06). A row of hydraulic actuated fingers which protrude from upper and lower main plane surfaces which on later marks had selectable IN MID and OUT positions, the ground crew hand signals for which made for much amusement as if repeatedly deployed and retracted caused the hapless “liney” to perform rather a silly dance relaying the position to the pilot. Ah memories. .

The F-15’s big speed-brake is a good example of a non-dive-brake; above 450 kts it is automatically retracted. Not a lot of use if you happen to be a vertical dive at that time…

Looks like the A-7’s big ventral barn door was designed as a dive-brake:

http://www.flightglobal.com/pdfarchive/view/1966/1966 – 1198.html

Specially designed divebrake adds substantially to the A-7A’s attack maneuvrability and mission accuracy

Yeah all of them…they are now called airbreaks lol.

Haha!

However I thought the difference was that dive-brakes were variable-extension and act to keep the terminal velocity below the Vne.

Air-brakes / speed-brakes are binary devices to momentarily reduce speed and, if mounted on wings, reduce lift. Airliners today use symmetrical spoilers as speed-brakes to increase rate of descent, exactly the opposite of what a dive-bomber needs.

Looking around on the net, dive-brakes seem to persist on gliders where it is critical that speed be limited in a dive without shedding lift, since it can’t be regained easily.